Since you are not going to be using all those PCIe slots, I'd consider a uATX motherboard.Typically, they're less expensive, and they have the same features and performance as the ATX formatted motherboards.

You could also buy a uATX case, although they are not generally less expensive than full-sized mid-towers.

I'd start reading the Haswell reviews. The reviews indicate Haswell runs hotter than Ivy Bridge and should have a beefier heatsink.

Also, check your power supply for compatibility with Haswell. PSUs that worked with Ivy Bridge may not be completely compatible with Haswell.

I'll look into uATX, though with all the HDs to house, I'm not sure they are a great buy? Particularly if there is no cost saving on the motherboard. I would also expect them to run hotter (less space for fans) and louder (smaller fans therefore higher RPM)?

It seems they only run hotter once you increase voltage. I will likely OC, but only to the level I can without a voltage increase. That heatsink isn't beefy!?

I check the list provided in another thread. It's in the probably compatible section.

I see that you're located in the UK, but if your heart's totally set on the Ballistix Sport RAM, Micro Center (US-based) seems to have some in stock, if you can find a trustworthy soul to pick up and ship to you.

I was going to recommend the Define Mini - it's a uATX, and has 6x 3.5" drive bays. I use one for my server, and it was formerly my main rig's case. The main rig is now in a Define XL R2. I think your R4 is a good choice.

I run 120mm Silent Typhoons in both the Mini and the XL R2. All the fan holes in both cases will take 120mm fans.

As for your RAM, I've had terrible luck with Ballistix RAM recently, I had 1866 stuff that wouldn't run at 1866, and I had some 1600 stuff that didn't run at all. I stick to Kingston HyperX RAM now, I've had excellent results from it, and I've been able to overclock the urine out of it and it keeps on coming back for more. I think I have 52GB of Kingston HyperX around here now.

I think you might struggle a little with the "near maximum" settings bit at 2560x1600 with a single 670. Depending on your definition of "near maximum", you probably won't be able to use much AA at those resolutions without taking a fairly severe performance hit.

I'm sticking to my 24" 1,920 x 1,200 for now. If I move to 27" or 30", I'll almost certainly upgrade my graphics card at the same time (see future upgrades in OP). Having considered it, I decided that for now it's more trouble than it's worth.

So the build went reasonably smoothly, if it did take longer than expected (1 hour to disassemble, 3 hours to assemble).

Issues that might be of use to others and some comments on the components:

1. Plugging in the 12V power lead to the mobo is a real pain in the ass if you have a huge heatsink like mine. The heatsink covers the socket and there is just no way to install it with the motherboard in place, at least not in the Fractal R4. I have to unscrew the motherboard and move it some way out of position to allow me to plug it in.

2. The Asus motherboard I bought only comes with 6 holes to screw it to the case. While this isn't a big deal, the fact that some of the holes are not at the corners means there can be considerable flexing if you put pressure in the wrong area.

3. My DVD-RW drive having installed Windows fine, refused to read the Asus driver DVD. I have no idea why, but in future, I'll make sure I have key drivers like LAN on a USB stick.

4. Being able to route the cables behind the motherboard tray is fantastic for tidiness. It can be a bit of a stretch for some cables (fans in particular) but overall I liked it a lot, as well as the mounting for the HDs.

5. The R4 isn't much quieter than my P180, despite having 3 x 140 fans mm fitted rather than 4 x 120 mm (one in the roof of the P180 no less), this surprised me.

6. The only real criticism I have of the R4 is the final finish. Screwing in the motherboard stand offs needed an adjustable spanner as there was no way I could do it by hand. Also the fit of one of the side panels is less than perfect.

7. The cooler is doing a good job so far. I'm seeing idle of 31C - it's surprisingly variable, from 27C up to 37C within seconds (ambient of 23C), and load of 51C so far using Prime95, though I only ran it for a few minutes. Not sure what it would get up to after a couple of hours of gaming.